Machine tool



April 21, 1942. I G. K. MCKEE" 2,280,596

- MACHINE TOOL Filed March 9, 1940 v 5 Sheets-Sheet 1 GEQRGE K. McKEE,

BY i 1% ATTORN I.

April 21, 1942.

G. K. M KE'E MACHINE TOOL Filed March 9, 1940 5 Sheets-Sheet 2 1 INVENTOR. GEORGE K. McMEE,

ATTORNEY.

April 21, 1942. aKMcKEE 2,280,596

MACHINE 'TOOL Filed March 9, 1940 5 Sheets-Sheet 4 V g INVENTOR. O W 76 "33: GEORGE l4. Makeo 15 BY v 4% 83 ATTORNEYS.

Patented Apr. 21, 1942 Ui'iED STATES MACHINETOQL Application March 9, 1940, Serial N 0. 323,181

7 Claims.

This invention relates to improvements in machine tools, and particularly to improvements in a tapping attachment or tapping mechanism for use with drilling machines.

An object of this invention is the provision of a mechanism for tapping bored holes, and in which the direction of rotation of the tap is readily reversed.

Another object of this invention is the provision of a tapping mechanism operable by a single lever arranged at the normal feed position of a drilling machine.

A further object of this invention is the provision of a drilling machine including a tap operating mechanism wherein a single lever is employed for operating the tap and the drill feeding and retracting mechanisms.

A further object of the invention is the provision of a drilling and tapping machine, operable from a single lever, and including means for determining whether a tapping operation or a drilling operation is to be performed.

A still further object of the invention is the provision of a drilling and tapping machine, that is, a machine capable of performing both drill- 3 ing and tapping operations, and in which the tapping mechanism may be completely and definitely locked out of operation.

Other objects and advantages of the present invention should be readily apparent by refer- Fi 1 is a front elevation of a drilling machine embodying the improvements of this invention.

Fig. 2 is a side elevation of the drilling machine shown in Fig. 1, as seen particularly from the right hand side of said Fig. 1.

Fig. 3 is an enlarged, vertical, sectional view through the spindle drive mechanism, taken on line 3-3 of Fig. 1.

Fig. 4 is a transverse, sectionalview through the speed change box of the spindle, drive mech anism, taken on line 4-4 of Fig. 3.

Fig. 5 is a vertical, sectional view through a portion of the speed change mechanism, taken on line 55 of Fig. 4.

Fig. 6 is an enlarged, vertical, sectional view .55

through the spindle quill support, taken on line 6-6 of Fig. 1.

Fig. 7 is an enlarged, transverseview showin in plan the tapping mechanism,.taken., on line 'l-l of Fig. 1.

Fig. 8 is a transverse, sectional view through the spindle quill feeding mechanism, taken on line 8-8.of Fig. 7.

Fig. 9 is a fragmentary, end elevational view of a portion of Fig. 8, as seen from the right hand end thereof.

Fig. 10 is a fragmentary, sectional view, taken on line |lii ll of Fig. 8.

Fig. 11 is, a longitudinal, fragmentary, sectional View, taken on line I l--I I of Fig. 8.

Fig. 12 is a vertical, sectional view, taken in a plane. ahead of Fig. 10, on line l2l2 of Fig. 11.

Fig. 13 is a view in elevation, taken just. behind the cover plate of the tapping attachment, :on line !3l3 of Fig. 8.

Fig. 14 is a fragmentary, sectional view, taken on line ,Ml4 of Fig. 13.

Fig, 15 is a view similar to Fig. 7, showing a modification in the mechanism for accomplishing the objects of this invention.

Fig. 16 is a longitudinal, sectional view through the spindle quill feeding mechanism andtapping attachment operating means.

Fig. 1'7 is a transverse, sectional view taken on line l'll'| of Fig. 16.

Fig. 18 is a view similar to Fig. 13, taken behind the cover plate of the modified tapping op eration control mechanism.

Fig. 19 is a transverse, sectional view, taken on line iii-l9 of Fig. 18.

Fig. 20 is a diagrammatic view illustrating the electrical mechanism effected and controlled by the mechanism previously referred to.

Fig. 21 is a diagrammatic view similar .to Fig. 20, illustrating a modification in the mechanism employed.

Throughout the several views of the drawings,

similar reference characters are. employed to denote the same or similar parts.

The control mechanism, or the so-called tapping attachment of this invention may be employed with various machine tools, and whileit will be described in connection with a particular machine tool, it will be understood it-has equal application to other machine tools having a rotary spindle axially operable for feedingpurposes.

Asshown in the drawings, the tapping attachprise a supporting base 25, from which rises a standard or column 26. The forward face of the column 26 is provided with a dove-tailed guide 21 received in a correspondingly shaped guideway formed through the rear end of a work supporting table 28. Any suitable means, not shown, may be employed for adjusting the work supporting table vertically of the guide 21.

Mounted on the standard 26 is a column 29 having its upper end goose necked or bent outwardly as at 39 and having secured thereto or integral therewith a housing 3|. The housing 3| is closed at its lower end by a plate 32 and has secured to the upper end a casing or gear box 33, in turn closed by a cover plate 34.

As seen in Fig. 3, the housing 3| is provided with anti-friction hearings in which is journaled the motor shaft 35 of an electric motor indicated in general by the reference character 36. In addition, the housing 3| carries antifriction bearings in which is .l'ournaled a driven sleeve 31, which carries keys 38 entering splines in the spindle 39.

The motor shaft 35 has projecting from it a splined drive shaft 46, on which is slidably mounted gear cluster 4| respectively adapted to engage with driven spur gears 42 fixed to the projecting end 43 of the driven sleeve 31. As will be noted from Fig. 3, the cover plate 34 carries suitable anti-friction bearings for providing the upper end of the motor shaft extension 49 and driven sleeve extension 43. In order to shift the gear cluster 4|, use is made of a shifter mechanism, comprising, see Figs. 4 and 5, a fork '44 integral with or secured to a sleeve 45, which has secured to its upper end means for forming a groove 46 to receive pin 41 at the inner end of an arm 48. The arm 48 is secured to one end of a stud 49, oscillatably jcurnaled in a bearing 59 provided by a bracket which is secured to the upper surface of cover plate 34. The remaining or outer end of the stud 49 has secured to it a lever 52 whereby the arm 46 is oscillated about the axis of the stud 45. It will be readily appreciated from Fig. 5 that the oscillation of the .arm 48 vertically, shifts the sleeve 45 and thereby the fork 44 and gear cluster 4|. In order to guide the sleeve 45 in its movement, it receives an upstanding stud 53 secured to and upstanding from the base of the gear housing or casing 33.

It should be here noted that the motor 36 of of the reversible type, and it will be appreciated from the foregoing that the motor 36, through its shaft 35 with gears 4| and 42 and driven sleeve 31, will drive the spindle 39 in reverse directions and at a speed depending on which of the gears of the gear cluster 4| is being meshed with its gear 42.

In order to axially move the drill, as when performing drilling or tapping operations, the' lower end of the spindle 39 is mounted in a sleeve or quill 54, which provides suitable anti-friction thrust bearings for the spindle. As seen in Fig. 6, the quill 54 is revolubly secured to the spindle by a nut 55 carried by threads 56 on the spindle and a shoulder provided by the drill and tap socket 51. The quill is mounted for sliding movement in an arm 58, which is adjustably secured through a dove-tailed guide-way at its rear end to a dove-tailed guiding tongue 59 projecting from the forward face of the column 29. In order to axially adjust the quill 54 and thereby the spindle 39 and parts carried thereby, the quill has secured to it a rack 69 which meshes with rack pinion 9| The rack pinion 6 see Fig.

8, is provided on each side thereof with a bearing portion 62 and 63, the former of which is journaled in a bearing bushing 64 carried by the arm 58, while the latter is journaled in a hearing provided directly by the arm 58. Outwardly of the bearing sleeve 63, the pinion 6| is provided with a counterbored sleeve 64a. Hereinafter, these parts will be referred to in their entirety as the rack pinion sleeve, which includes the rack pinion, the bearing sleeves 62 and 63 and the projecting sleeve 54a. Mounted in the rack pinion sleeve is a lever or bar 65, actuation of I which in either direction correspondingly actuates the pinion 9! and quill 54.

The foregoing is more or less conventional construction, in so far as the feeding and re traction of the quill is effected by the manual rotation of a pinion 6| and thereby the axial movement of the quill.

As seen in Fig. 8, the rack pinion is hollow and has disposed therein a shaft 66 which is provided at its outer end with a head 61. The head 61 is disposed in a counterbore 68 in the proecting portion 64a of the rack pinion sleeve, and this head has abutting its under surface one end of a spring 69, whose other end abuts the base 19 of the counterbore 68. In order to prevent rotation of the shaft 66, its head 61 is provided with a slot receiving the nose of a set screw 1|, thereby insuring merely an axial movement of the shaft 66 and its head 61. The outer end of the head 61 is provided with a seat 12, in which is disposed a pin 13, which extends entirely across the counterbore 68, as clearly illustrated in Fig. 11. The other side of the pin 13 is disposed in a pair of V-notches 14 and 15, formed at the inner end of a counterbored plug 16. The plug 16 has passing through it the said lever 65, and in order to hold the lever 65 yieldably, the plug 16 houses a spring pressed ball 11, which engages against the adjacent face of the lever 65 and the yielding tension of which ball 11 is adjustable by a screw plug 18 which bears against a spring 19, which in turn bears against the ball 11. The aperture through the rack pinion sleeve through which the lever 65 passes is elongated as at in Figs. '1 and 12, and the purpose of which will be subsequently described.

Secured to the arm 58 on the side opposite to that from which the pinion sleeve extension projects, as by means of a lug 8|, is a housing 92 which encloses the tapping control mechanism, and which is operated by the shaft 66. The housing 82 has one end provided with an aperture 83, whereby the control mechanism enters the housing and has its other end suitably closed by a cover plate 84. Secured to one side 85 of the housing 82 and intericrly thereof, is a bracket 86 supporting a switch 81. In addition, the bracket 86 has depending therefrom a pair of arms 88 and 89, between which is pivotally mounted, as at 96, a rocker member 9|. The rocker member 9| may be conveniently provided with a knob 92, which engages the push button 93 of the switch 81. The rear end of the rocker member 9| is straight or vertical, as at 94, and rests against one vertical face of a lever 95. The lever 95 has its bottom face resting on the upper end of a reduced portion 96 of the shaft 66 and finally the lever 95 has its other vertical face engaging with the shoulder 91 provided at the base of the shaft reduced portion 96. Also, the lever 95 has projecting from it a pin 98, whose inner fiat surface engages with the end of the pinion bearing sleeve 64.

The lever 95 projects laterally of the housing 82 and has one end projecting therebeyond, and which projecting end is pivoted at 99 to the fork end I of a pivot IIlI. Projecting from the pivot IIII is a pivot pin I62 oscillatably disposed in a bore in a lug I63 projecting laterally from the housing 82. Integral with and projecting angularly upwardly and outwardly from the lever 95, is a lever I24, which, together form a bell crank pivoted at the junction of the arms of the crank. The portion I32 of the bell crank, at its upper end, is enlarged as at I05.

From the foregoing, it will be noted that the bell crank lever 95I64 is mounted for vertical oscillation by the pivot 99 and horizontal oscillation by the pivot IIlI. In order to return the arm to the position shown, which may be termed the normal position, use is made of a leaf spring I66 secured to the housing 85 by the bracket 86,

and having its upper end engaging with the lever The operation of the mechanism thus far described is as follows:

When either drilling or tapping, the lever 65 is actuated toward the operator, as seen in Fig.

shaft 66 and the head 61 and compressing the spring 65. This movement of the shaft 66, through its shoulder 91, oscillates the bell crank 95I04 about the vertical axis of the pivot NH, and this lever actuates the rocker member SI in a clockwise direction about its pivot 96 for actuating switch push button 93 and closing the contacts of switch 81. As will later be pointed out, the closing of the switch contacts 81 starts the rotation of the motor in a drilling or advance tapping direction.

After the tap has finished its tapping operation, the lever 65 is actuated away from the operator, as seen in Fig. 8, or in a clockwise direction, as seen in Fig. 12, thereby lining up the cradles 14 and with the transverse pin 13 and allowing the spring 69 to return the parts to the position shown in Fig. 8, whereupon a spring associated with the push button 92 pushes the same to the position shown for completing an electrical circuit for reversing the direction of rotation of the spindle drive motor, and backing the tap from the work.

In order to hold the lever 65 in either its tap advancing or tap retracting positions, use is made of a yieldable detent, illustrated most clearly in Figs. '9 and 11. As shown in Fig. 11, the plug 16 has projecting from one side thereof a pin I06 which lies parallel to and adjacent the end of the pinion sleeve extension 64a. Co-operating with the pin I66 is the detent dog I61 disposed within a bore in the pinion sleeve extension 64a, and which dog is backed by a spring I63 abutting on one end with the dog and on its other end the base of the bore.

In the event it is desired to do merely plain drilling operations, and not operate a tap, the handle 65 may be locked against movement for reversing the switch 81. This mechanism is illustrated in Fig. 12, and comprises a jam screw I69 threaded into a tapped aperture III] extending angularly of the counter bore 68,. in the pinion sleeve extension 6441. As willibe seen from Fig. 12, by screwing the jam screw I69 downwardly, the handle 65 will be madeflto takeup the play in the elongated aperture 80, thereby closing the switch 81 .and preventing the reverse operation of this switch, and causing the drill spindle to rotate in a forward or drilling direction at all times, even though the handle. 65 is actuated to retract the drill.

This result, namely therotation of the motor in a forward .or drilling direction, regardless of how the handle 65 is actuated, may be accomplished electrically. For this reason, there is mounted within the switch housing 82, a second switch III operable by ,a toggle lever II2 which projects through the switch housing 32 thereabove.

In Fig. 20, there is illustrated diagrammatically the electrical mechanism and switches operated by the above described mechanism. As there shown, the toggle switch I II has two of its fixed contacts H3 and H4 electrically connected by wire I I5 with wire I I6 of the main power source. A third fixed contact H1, is connected by a wire II8 with a fixed contact II9 of the switch 31. The fourth fixed contact I of the toggle switch III is connected by wires IZI and I22 with fixed contacts I23 and I24 of switch 81. The fixed contact II1 of toggle switch III and the fixed contact H9 of limit switch, 81, are further connected with one end of the solenoid coil I25 of solenoid switch I26, as well as fixed contact I21 of solenoid switch I26. The other end of solenoid coil I25 is connected by wire I28with a second wire I23 of the power source, and this main wire I29. is connected by wires I30 and I3I with a second fixed contact I32 of solenoid switch I26. The third wire I33 of the main power source is connected by wires I34 and I35 with a third fixed contact I36 of the solenoid switch I26.

The solenoid switch I26 includes three bar switches I31, I38 and I39, adapted respectively to connect the fixed contacts I32, I21 and I36 with companion fixed contacts respectively indicated by reference characters I 32', I21 and I36. The fixed contact I32 is connected by wires I60 and MI with the. field coils of the spindle rotating motor 36; the fixed contact I21 is connected by wires I42 and I43 with said field coils of the motor 36, while the fixed contact I36 is connectedby wires I M and I 45 with the motor field coils.

From the foregoing, and with the toggle switch in the position illustrated in Fig. 20, which is the drilling position exclusively, the coil I25 is energized for closing the solenoid switch contacts and effecting the rotation of the motor 35 in the drilling direction. This drilling direction rotation of the motor will continue, regardless of the position of the switch 81, since even though it is actuated, it can exercise no effect on the parts. If, now, the toggle switch III is actuated to its other position for electrically connecting fixed contacts H3 and IZfl'thereof, then the operation of. the switch 81 does control the direction of rotation of the motor.

The switch 81 has a fourth contact I46 which is electrically connected by a wire I41 with one end of a coil I48 of a second solenoid switch I49. The coil I48 has its other end connected by wires I50 and I36 with the power line I29. The solenoid switch I49, similar to the solenoid switch I26, has three pairs of fixed contacts I5I and I5I', I52 and I52 and I53 and IE3". These pairs of fixed contacts are adapted to be bridged by .bar contacts I64, I65 and I66 respectively. The contact I5I is connected by wires I54 and I34 with the power line I33, while its companion contact I5I is connected by wires I55 and I to the field coil of motor 36. The fixed contact I52 is connected with the contact I46 of the switch 81 by a wire I56, while its companion contact I52 is connected by wires I51 and MI with the field coil of the motor 36. The contact I53 is connected with the power line I29 by the wire I30, while its companion contact I53 is connected by wires I58 and I43 with the field coil of the motor 36. The contact I46 of the switch 81 is connected by bar contact I59 with the contact I24 and through lines I22 and I2I, toggle switch III and wire II5 with the power line H6. The fixed contact II9 of the switch 81 is likewise connected with contact I23 by a bar contact I60 and through lines I22 and HI, toggle switch III and wire II5 with the power line II6.

From the foregoing, it will be noted that with the toggle switch in the second position from that shown in Fig. 20, namely, connecting contacts I I3 and I20, and with the switch 61 in the position shown, the solenoid switch I26 is closed for connecting, first, power line I29 with the field coil at point I6I, second, power line II6 with the field coil at point I62 and third, power line I33 with the field coil at point I63. ing of the switch 81 through the actuation of handle 65, the electrical connection of contacts H9 and I23 is broken and an electrical connec: tion established across contacts I24 and I26, thereby de-energizing solenoid switch I26 and energizing solenoid switch I49. The closing of the solenoid switch I49 connects the power line I33 with the motor field coil at point I63 the same as solenoid switch I26 did. The power line H6 is now connected with the motor field coil at point I6I instead of at point I62 as did the solenoid switch I26 and the power line I29 is connected with the motor field coil at point I82 instead of point I6I, as did the solenoid I26. In other words, the field coil excitation is reversed for thereby reversing the direction of rotation of the motor 36 and backing off the tap.

As is frequently necessary, so-called blind holes are tapped, that is, holes which do not go entirely through the work piece but go down a certain depth to bottom. In drilling holes of thi nature, the same operation as above described is effected, that is, the handle 65 is actuated toward the operator, as seen in Fig. 8, for shifting the shaft 66 and actuating the rocker member 9| in a counterclockwise direction. The motor is then rotating in a direction for tapping, and the tap is fed into the hole by continuing to pull on the lever 65. When the tap is at the bottom of the blind hole, a dog screw engages the head I05 on the lever I64 of the bell crank 95I04. This dog screw, indicated in the drawings by reference numeral I61, is adjustably mounted in a threaded aperture in an arm I68 which has at its other end a ring I69 that encircles the drill quill 59, all as clearly illustrated in Figs. 7 and 13. As will be seen from these figures, the ring I69 is provided with a clamp screw I10, whereby its longitudinal position is adjustable with respect to the quill 54. As further seen from Fig. 7, the parts are so arranged as to have the dog screw I 61 directly over the head I05 of arm I04.

Upon the shift- The operation of this depth tapping mechanism is as follows:

The engagement of the dog screw I61 with the head I05 actuates the bell crank 95-I04 in a clockwise direction about the axis of the pivot 99, thereby raising the arm 95 above the shaft shoulder 91. This then releases the pressure on the spring associated with the push button 93 of the switch 81, so that said spring actuates the rocker member 9| in a counterclockwise direction, forcing the lever 35, which is now above the shoulder 91, to the right, as seen in Fig. 8, about the axis of the pivot IN. This then immediately reverses the direction of rotation of the motor 36 and the tap is backed out of the hole by reversely actuating the lever 65.

It should be noted that the movement of the lever 95 by the pusher 9| about the axis of the pivot IOI is limited by the engagement of the pin 98, projecting from the lever 95, engaging with the end of the. pinion sleeve extension 62 and with the said lever resting on the surface of the shaft 66, but ahead of the shoulder 91. When the lever 65 is actuated to retract the tap from the hole, the shaft 66 is actuated to the right, as seen in Fig. 8, and therefore retracts the shoulder 91 to a point ahead of the lever 95, and said lever, due to the leaf spring I06 is then actuated behind the shoulder 91 and to its normal position for resetting the motor for a subsequent tapping operation.

In Figs. 15 to 19 inclusive, a tapping mechanism is disclosed which accomplishes the same purposes as that above, different, however, in mechanical detail. Specifically, this modified structure comprises a pinion sleeve, including the pinion I1I, having extensions I12 and I13, the former of which is journaled in a bushing I14 pressed into the arm or bracket 58, while the latter spindle extension I13 is journaled directly in the arm 58. Mounted on the outer surface of the pinion sleeve extension E13 is a slidable sleeve I15 having a radial flange 16 at its inner end. Secured to the outer end of the slidable sleeve I15 is a plug I11, through which passes the handle 65, retained in position by a yieldable plug I18, similar to the ball 11 above referred to. The plug I11 has projecting inwardly thereof a spindle I19 adapted to abut with the inner end of a lock out screw I80.

The sliding sleeve I15, see Fig. 15, is provided at diagrammatically opposite points with an elongated angularly disposed aperture I8I, in one of which is disposed a roller I82 carried by the pinion sleeve extension 113 and held in position by a headed stud I83. In the other elongated aperture I8I is the head I84 of a screw I65.

Engaging ahead of the radial flange I16 of the sliding sleeve I15 is one end of a lever I86 which is pivotally mounted intermediate its ends at I81 in the forked end of a pivot member I88. The pivot member I88 has projecting therefrom a shaft I89, journaled in suitable bearings Provided by a switch housing 82 which, while diiferent in external configuration, is substantially identical to the switch housing 82 above described. Between the shaft bearings, and within the housing 82, the shaft I69 has secured thereto a lever I90 adapted to have its free end engaged with and operate the push button 93 of a switch 81 which is similar in all respects to the switch 81 above referred to. The lever I86 is yieldably biased by the leaf spring I9I to at all times asume the normal position illustrated in the drawings. Aswill 'be seen from Fig. 18, the switch housing 82 contains a toggle switch III which is identical to the toggle switch above referred toand described.

The operation of the mechanism is as follows:

When it is desired to effect a tapping operation, the lever '65 is actuated toward the operator for first rotating and longitudinally sliding the sliding sleeve I75 and which sliding is effected by oamming operation of the elongated angular aperture I8! on the roller I82. This causes the radial flange I 76 to shift the lever I86 downwardly in Fig. 15 or toward the observer in Fig. 18, and actuates the pivot member m8 and its shaft I39 in a clockwise direction, as seen in Fig. 15, or toward the observer in Fig. 18, for actuating the switch push button 93. 'This closes the proper contacts within the switch 87, or, as seen in Fig. 20, within the switch 8'5, for effecting a tapping operation. When the tapping operation is completed, and it is desired to retract the tap, the lever 65 is reversely operated, or pushed away from the operator, for first shifting thelidi-ng sleeve I'i5 to the left, as seen in Fig. 15, and returning the. parts to their normal position, whereupon the motor 36 is reversed and the tap retracted.

As was noted above, in this modified structure, use is made of the toggle switch III, which, as abovefdescri'bed, to electrically lock out the revers'ing switch 87' so that the operation of the handle 65 will not control the direction of rotatap reversing switch tipn of the motor 35. In order to do this mechanically, use is made of thelock out screw I883 by turning said screw to actuate the plug I18 and its spindle I19 to the right, as seen in Fig. 16, and allowing no play between these parts, which is normally there between the elongated aperture I8I and its roller I82 Sui-Hoe it to say that the elect ric wiring of Fig. 20 equal application to the mechanism just described as to that initially described.

The wiring diagram in Fig. 211 differs from that infig. 20 to the extent that a combination solehold and gravity switch L72 is employed instead of a pair of solenoid switches, In other words, with the parts in the position illustrated, the solenoid coil I93 is energized for closing the switch and rotating the motor 36 in one direction. Upon de-energization of the solenoid coil I93, the switch drops by gravity to break the initial setting, establishing a switch connection for reversely actuating the motor 38. It is believed, in view of the minute description of Fig. 20, that a further description of Fig. 21 is unnecessary. There has, however, for purpose of comparison, been applied to Fig. 21 the same reference characters of Fig. 20, with the addition thereto of a prime mark.

It is believed from the foregoing, that it is now evident that there has been provided a tapping attachment for drilling machines and the like which will meet all of the objects initially set forth.

What is claimed is:

1. In a machine tool of the class described having a spindle mounted for reverse rotation and reverse axial translation, a reversible motor for rotating the spindle, and a manually rotatable rack and pinion mechanism for translating the spindle, the combination of a lever for operating the rack and pinion mechanism, the connection of the lever with the rack and pinion providing a small amount of lost motion for the lever, a

reversing switch for controlling the rotation of the motor, an arm pivotally mounted for actuating the switch, a cam associated with and operated by the lever, and a member axially movable by the cam and lever during the movement of the lever to take up the lost motion between itself and the rack and pinion for actuating the arm to operate the switch and rotate themotor in aforward direction prior to the actuation of the rack and pinion mechanism by the lever.

2. In a machine tool of the class described having a spindle mounted for reverse rotation and reverse axial-translation, a reversible motor for rotating the spindle, and a manually rotatable rack and pinion mechanism for translating the spindle, the combination of a lever for operating the rack and pinion mechanism, the connection of the lever with the rack and pinion providing a small amount of lost motion for the lever, a reversing switch for controlling the rotation of the motor, an arm pivotally mounted for actuating the switch, a cam associated with and- 0perated by the lever, and a member axially-movable by the cam and lever during the movement of the lever to take up the lost motion between itself and the rack and pinion for actuating the arm to operate the switch and rotate the motor in a forward direction prior to the actuation of the rack and pinion mechanism by the lever, said switch being adapted to be reversely operated upon reverse actuation of the lever for reversely rotating the motor.

3. In a machine tool of the class described having a spindle mounted for reverse rotation and reverse translation, a reversible motor for effecting the spindle rotation, and a rack and pinion mechanism for effecting reverse translation, the combination of a lever for operating the rack and pinion mechanism, the connection of the lever with the rack and pinion providing a' small amount of lost motion for the level a reversing switch for the motor, a pivotally mounted arm for operating the switch in one direction and whi'ch switch is yiel'dably operated in the other direction, a cam associated with and oper ated by the lever and a member axially movable inone direction by the cam upon operation of the lever during the movement thereof to take up the lost motion for actuating the arm and switch to effect rotation of the motor in one direction prior to the actuation of the rack and pinion mechanism by the lever and said member being axially movable in the opposite direction upon reverse actuation of the lever and cam to permit reverse operation of the switch and rotation of the motor in the reverse direction.

4. In a machine tool of the class described having a spindle mounted for reverse rotation and reverse translation, a reversible motor for effecting the spindle rotation, and a rack and pinion mechanism for effecting reverse translation, the combination of a lever for operating the rack and pinion mechanism, the connection of the lever with the rack and pinion providing a small amount of lost motion for the lever, a reversing switch for the motor, a pivotally mounted arm for operating the switch in one direction and which switch is yieldably operated in the other direction, a cam associated with and operated by the lover, a member axially movable in one direction by the cam upon operation of the lever during the movement thereof to take up the lost motion for actuating the arm and switch to effect rotation of the motor in one direction prior to the actuation of the rack and pinion mechanism by the lever and said member being axially movable in the opposite direction upon reverse actuation of the lever and cam to permit reverse operation of the switch and rotation of the motor in the reverse direction, and a selector switch electrically connected across the reversing switch to prevent operation of said reversing switch by the lever.

5. In a machine tool of the class described having-a spindle mounted for reverse rotation and reverse translation, a reversible motor for effecting the spindle rotation, and a rack and pinion mechanism for effecting reverse translation, the combination of a lever for operating the rack and pinion mechanism, the connection of the lever with the rack and pinion providing a small amount of lost motion for the lever, a reversing switch for the motor, a pivotally mounted arm for operating the switch in one direction and which switch is yieldably operated in the other direction, a cam associated with and operated by the lever, a member axially movable in one direction by the cam upon operation of the lever during the movement thereof to take up the lost motion for actuating the arm and switch to effect rotation of the motor in one direction prior to the actuation of the rack and pinion mechanism by the lever and said member being axially movable in the opposite direction upon reverse actuation of the lever and cam to permit reverse operation of the switch and rotation of the motor in the reverse direction, and means for actuating the lever to take up the lost motion thereof and lock the lever in this position to effect axial movement of the member to operate and lock the pivotally mounted arm and switch for rotating the motor in one direction only even upon reverse actuation of the lever.

6. In a machine tool of the class described having a spindle mounted for reverse rotation and reverse translation, a reversible motor for efiecting the spindle rotation, and a rack and pinion mechanism for effecting reverse translation, the combination of a lever for operating the rack and pinion mechanism, the connection of the lever with the rack and pinion providing a small amount of lost motion for the lever, a reversing switch for the motor, a pivotally mounted arm for operating the switch in one direction and which switch is yieldably operated in the other direction, a cam associated with and operated by the lever, a member axially movable in one direction by the cam upon operation of the lever during the movement thereof to take up the lost motion for actuating the arm and switch to effect rotation of the motor in one direction prior to the actuation of the rack and pinion mechanism by the lever, and said member being axially movable in the opposite direction upon reverse actuation of the lever and cam to permit reverse operation of the switch and rotation of the motor in the reverse direction, said arm having a second pivotal mounting for movement in a direction normal to that given it by the axially movable member, and means operable independently of the lever for actuating the arm about its second pivotal mounting while the lever is in the position for holding the switch in a position for rotating the motor in one direction and thereby permitting the operation of the reversing switch to effect the rotation of the motor in a reverse direction.

7. In a machine tool of the class described having a spindle mounted for reverse rotation and reverse axial translation, a reversible motor for effecting the spindle rotation, and manually operable rack and pinion mechanism for effecting the spindle translation, the combination of a manually operable lever, means for mounting the lever on the pinion of the rack and pinion mechanism for limited independent movement prior to an actuation of the pinion thereby, an axially movable member, a pivotally mounted switch arm, a reversing switch adapted to be operated by the switch arm to cause motor rotation in a forward direction and adapted to independently operate to cause a motor rotation in a reverse direction, a cam associated with and operable by the lever during its independent movement relative to the pinion for effecting the axial movement of the axially movable member and the operation of the switch, said cam and axially movable member being reversely actuated by the switch upon reverse operation of the lever to permit the switch operation and motor reversal, and a selector switch electrically connected across the reversing switch to prevent reversal of the motor and effect continuous forward movement thereof regardless of the operation of the axially movable member.

GEORGE K. McKEE. 

